Strain Partitioning at the Oxide Interface for the Isothermal Phase Transition in Freestanding Tri‐Layers

Abstract A delicate interplay between lattice and charge provides a unique strategy to control the strain‐driven stability of the electronic phase in quantum materials featuring metal–insulator transition (MIT). The strain‐induced modification of the ionic bonding network has been utilized to tune the transition temperature ( T MI ) of VO 2 by changing the band occupancy of d electrons. Still, previous approaches prevent the maintenance of a steep phase transition due to the introduction of structural disorders. Herein, strain partitioning is exploited using freestanding tri‐layers for the unrestricted T MI change without losing transition quality. Using the strategy to release freestanding TiO 2 /VO 2 /TiO 2 tri‐layers with different thickness ratios (), strain partitioning by the thickness of TiO 2 layers () systematically control electronic phase stability in sandwiched VO 2 layers without the introduction of the disorder; remarkably, extensive resistance modulation (Δ R / R ∼ 1.0 × 10 3 ) and steep transition (Δ T h , Δ T c = 2.5 K) are achieved in T MI ‐tuned VO 2 layer in terms of both electrical and optical characteristics. The freestanding tri‐layer design will provide a new strategy to unrestrictedly tune T MI in the VO 2 layer by simply changing the thickness of strain‐partitioning layers () and offer a unique opportunity to design strain‐tunable functionality using emergent materials.